The shape of a typical ship's hull is designed to minimize the drag of the water on the ship such that it travels on the surface of the water as efficiently as possible. This can be seen in the vast majority of large-waterplane-area ship's today in their long and sleek look. A large-waterplane-area ship, which garners the majority of its buoyancy from the amount of surface area of the hull that meets the plane of water, can be distinguished from a small waterplane area ship, which garners the majority of its buoyancy from underwater displacement pontoons. The long and narrow hull of a large-waterplane-area ship minimizes the effects of the water on the acceleration and velocity of the ship. As a general rule, the longer the length of the hull is with respect to its width, the more efficient the vessel operates.
Several physical factors affect the operation of both small and large-waterplane-area ships. For example, strong headwinds or other wind resistance will affect the velocity and acceleration of a ship. In another example, the friction of the water against the ship constantly works against the velocity of the ship. Another physical factor, discussed in greater depth below, is the wave drag of a ship. That is, the effect of the ship's own wake working against its velocity.
It is well known in the art that a Froude number may be used to mathematically express the efficiency of the ship's hull design with respect to wave drag. The ship's Froude number is defined as follows:                F=v/sqrt(g*l),        v=velocity,        g=acceleration of gravity, and        I=length of hull.        
The effect of wave drag on a ship's velocity is described in Modern Ship Design, by Thomas C. Gillmer, 1970 which states, “The practical limiting speed for displacement surface vessels is basically that of wavelength to ship length, where one wavelength, created by the ship, is equal to the ship's waterline length.” For efficient operation from the standpoint of powering and fuel consumption, typical ships have a velocity limit corresponding to a Froude number of 0.4. When a ship attempts to exceed this velocity limit, the drag of the water increases exponentially and the resulting power required to overcome the additional drag leads to extreme inefficiency. As a result, a ship is not typically designed with such propulsion requirements in mind.
FIG. 1 is a graph of a typical ship's wave drag (Cw) versus its Froude number. As can be seen, at low Froude numbers the wave drag is relatively low, proportionally increasing as the Froude number increases. An increase in the Froude number represents an increase in the velocity of the ship which corresponds to an increase in wave drag Cw. However, when the ship's velocity reaches the point corresponding to a Froude number of 0.4, the wave drag Cw increases exponentially with respect to an increase in the ship's velocity. This increase in wave drag Cw is well established in the prior art for all surface displacement ships and is often referred to as the resistance or powering “hump” 100. A hull experiences peak wave drag Cw in the center of the hump 100, which corresponds to a Froude number of 0.5.
Because of the high wave drag Cw, operation in the hump 100 region requires high propulsion power which leads to inefficient fuel usage. A ship that requires a constant operational velocity for a long time should not do so in the hump 100 region. As a result, the overall length of a ship's hull designed today is typically increased to allow the ship to reach greater velocities before the Froude number reaches 0.4. That is, most large-waterplane-area ships are designed to operate below the hump 100.
For example, FIG. 2 is a plan view of a conventional ship 200 having a relatively large overall hull length 205 as compared to its width W. The ship 200 is designed to operate at velocities corresponding to Froude numbers less than 0.4. If greater velocities are desired, one can design the ship's hull to be longer such that the 0.4 Froude number corresponds to a higher velocity than before. The alternative is to provide enough propulsion power to overcome the hump 100, such as with modern Destroyers or other high speed ships. Both solutions are inefficient because space is wasted by either increasing the length of the hull or the amount of propulsion power. As a result, it is difficult to efficiently gain velocity beyond a Froude number of 0.4 in large-waterplane-area ships.
It is also known in the art that operating a ship at a velocity having a corresponding Froude number greater than 0.8 substantially reduces wave drag Cw. Again referring to FIG. 1, one can see that the amount of wave drag Cw is substantially the same at a Froude number of 0.8 as it is for a Froude number of 0.4. That is, once the velocity of the ship overcomes the high wave drag Cw of the hump 100, additional increases in velocity do not require an exponential increase in propulsion power.
One such ship designed to operate at velocities corresponding to Froude numbers greater than 0.8 is disclosed in U.S. Pat. No. 5,592,895, entitled SMALL WATERPLANE AREA HIGH SPEED SHIP to Schmidt, which is assigned to the Lockheed Missiles and Space Co. and which is incorporated by reference. In this disclosure, Schmidt describes a small waterplane ship designed to operate at high speeds corresponding to Froude numbers greater than 0.8. Specifically, Schmidt disregards the convention of designing a hull to be as long as possible to attain greater velocities before the Froude number reaches 0.4 by disclosing a ship with a short hull wherein the hump 100 is overcome at fairly low velocities. The short hull, however, limits the size of the ship and the concept is not practicable for large-waterplane-area ships that require substantial payload capabilities.
Therefore, it is desirable to have a large-waterplane-area ship that reaches and surpasses the hump 100 at a low velocity such that the ship's operational velocity or cruising velocity is above the hump 100 at a high Froude number while also having a hull that provides substantial payload capacity.